1. Field of the Invention
The present invention relates generally to master links which connect ends of track chains of endless tracks to each other and, more particularly, to a method of manufacturing a master link which includes a pair of partial link units that are separably coupled to each other, and which can markedly enhance the degree of precision in machining the partial link units and the quality of the product.
2. Description of the Related Art
Endless tracks are used in crawler type vehicles, such as bulldozers or excavators. Such an endless track includes a plurality of track chain links which are rotatably connected one after another. A track shoe is provided on each track chain link. Ends of the track chain links are removably connected to each other by master links.
Such a master link for an endless track is an element which connects corresponding ends of the track chain links to each other. The master link includes two partial link units which are fitted to each other. Each partial link unit has an assembly portion. Assembling the two partial link units includes engaging their assembly portions with each other and fastening the partial link units to each other using a coupler.
The master link is manufactured by heating material, hot forging, heat treatment, planning both sides, boring holes for pins and bushings, drilling coupling portions, high-frequency treatment of portions to be worn by friction, a primary cutting operation for forming partial link units, a secondary cutting operation for machining the partial link units, and tapping the coupling portions.
Particularly, given characteristics of the assembly portions of the partial link units of the master link, the partial link units are formed by conducting the primary cutting operation using wire-cutting and the secondary cutting operation for forming a gap between the assembly portions.
However, in the conventional master link manufacturing method, only wire-cutting is used when dividing the master link into the two partial link units and forming the assembly portions of the partial link units. Therefore, process speed is comparatively low and cutting error is increased, thus reducing the degree of precision and the quality of the product.